page_title: Freshwater snail
section_title: Heterobranchia
hierarchical_section_title: Freshwater snail / Heterobranchia
caption_attribution_description: English: photo of Acochlidium fijiiensis
context_page_description: Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs to major rivers. The great majority of freshwater gastropods have a shell, with very few exceptions. Some groups of snails that live in freshwater respire using gills, whereas other groups need to reach the surface to breathe air. In addition, some are amphibious and have both gills and a lung. Most feed on algae, but many are detritivores and some are filter feeders.
  According to a 2008 review of the taxonomy, there are about 4,000 species of freshwater gastropods.
  At least 33–38 independent lineages of gastropods have successfully colonized freshwater environments. It is not possible to quantify the exact number of these lineages yet, because they have yet to be clarified within the Cerithioidea. From six to eight of these independent lineages occur in North America.
context_section_description: Lower Heterobranchia
  Glacidorbidae - 20 species.
  Valvatidae, small low-spired snails referred to as "valve snails". 71 species.
  Acochlidiacea
  Acochlidiidae (including synonym Strubelliidae) - 5 shell-less species: Acochlidium amboinense, Acochlidium bayerfehlmanni, Acochlidium fijiiensis, Palliohedyle sutteri and Strubellia paradoxa
  Tantulidae - there is only one species which is shell-less Tantulum elegans.
  Pulmonata, Basommatophora
  Basommatophorans are pulmonate or air-breathing aquatic snails, characterized by having their eyes located at the base of their tentacles, rather than at the tips, as in the true land snails Stylommatophora. The majority of basommatophorans have shells that are thin, translucent, and relatively colorless, and all five freshwater basommatophoran families lack an operculum.
  Chilinidae, small to medium-sized snails confined to temperate and cold South America. About 15 species.
  Latiidae, small limpet-like snails confined to New Zealand. One or three species.
  Acroloxidae - about 40 species.
  Lymnaeidae, found worldwide, but are most numerous in temperate and northern regions. These are the dextral (right-handed) pond snails. About 100 species.
  Planorbidae, "rams horn" snails, with a worldwide distribution. About 250 species.
  Physidae, left-handed (sinistral) "pouch snails", native to Europe, Asia, North America. About 80 species.
caption: Acochlidium fijiiensis is one of very few freshwater gastropods without a shell.
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